1. Field of the Invention
The invention relates to a process for producing high speed transmitting dielectric material, and in particular, to a process for producing high speed transmitting dielectric material by reacting directly polyphenylene ether (PPE) with an epoxy, characterized in that said PPE needs not to be cleaved into small molecules, and can therefore shorten greatly the reaction time. The process of the invention is applicable in the manufacture of printed circuit board material used in wireless communication, base station and the like.
2. Description of the Prior Art
Conventional processes for producing high speed transmitting dielectric material comprised of, as shown in FIGS. 7 and 8, cleaving firstly a polyphenylene ether (PPE) (A) of high molecular weight into PPE (B) of small molecular weight through chain cleavage with a peroxides, and then, after mixing with an epoxy resin (C) (a solvent-type epoxy of low bromine content), carrying out a reaction in the presence of a catalyst and a hardener to produce dielectric materials such as a prepreg, copper-clad laminate (CCL) and the like.
However, the above-described conventional processes had the following disadvantages:    1. Since current high frequency substrates or wireless communication substrates must have a certain specification, for example, when the specification of a product regulates the substrate at a thickness of below 1.6 mm, a dielectric constant of less than 4.0 and a loss factor of below 0.01, the original characteristics of high frequency substrates or wireless communication substrates can be retained subsequently. Under this circumstance, the high speed transmitting dielectric material produced by conventional processes based on the cleavage of PPE of high molecular weight may not meet requirements of current application.    2. PPE of this specification is used only in some particular manufacturers, and has high cost. In case to be mixed with other materials, PPE of high molecular weight has to be mixed with an epoxy resin only after being cleaved into PPE of small molecular weight. Moreover, since a number of factors such as, for example, the amount of the catalyst used, the reaction temperature, the desired small molecular weight and the like must be considered in the cleavage process, these processes were considerably time-consuming.    3. In conventional process, PPE of high molecular weight must be subjected to chain cleavage, reaction and formulating in the presence of a peroxide as the catalyst under high temperature, these all increase risks of those process.
In view of the forgoing, for improving the above-mentioned disadvantages such that PPE of high molecular weight can be mixed directly with an epoxy without necessity to subjected to chain cleavage and as a result, time required for chain cleavage can be eliminated as well as risks and problems occurred during the chain cleavage, the inventor had studied and carried out experiments extensively for many years based on his experience, and finally, developed the present invention.